Detection of crystal lattice defects in microranges of copper by X-ray interferences

Abstract

The lattice source interferences (LSI) or Kossel technique and the divergent beam X-ray interferences (DBI) or pseudo-Kossel technique are highly sensitive to the real structure in the microrange of the crystal lattice. Both methods complement each other, owing to their geometrically different diffraction regions. Mechanically ground and polished Cu single crystals with different crystallographic orientations ([100], [110], [621], [694]) and two polycrystalline Cu specimens were chemically etched stepwise with FeCl ₃ ·6H ₂ O. After each etching time, divergent beam X-ray patterns of the crystals were taken and in some cases lattice source interferences pattern also. It was possible to observe the real structure as a function of the depth, because the information comes from a depth of about 2-5 µm for LSI and 50-100 µm for DBI. The DBI patterns show, for instance, for Cu [100], sharp interference lines from regions up to 40 µm deep. With increasing depth the crystal lattice reveals the real structure only and not the deformation effect caused by polishing.